well bards are DD and support, they have a whole arsenal of stuff for the group and a ranger is a DD thats it lol, i really dont know what else it could do lol except if built decent it could tank.
i have a 20 Ranger and a 20 Bard. Ummm both are pretty fun. Ranger is mainly a dd. A bard can be basically anything you want. A bard can be a dd, healer, tank, and mana giver.
Ranger does have some support buffs, as well as a cm target heal and def shield, but as was said above they're primarily dd, just not as focused on it as say, a rogue. Bards are considered jacks of all trades. They have group heal ticks, ac buffs, mana regen, stat mods, etc, as well as mob DoTs and debuffs, and have a choice in two class support paths. One is a more powerful group PoT and the other was a group combat buff, but I think that's been made into an attack, giving more offensive flexibility. One thing to note about playing a bard... in a good grind they shouldn't get a chance to chat much, lol. Their buffs are only about 2 minutes long iirc (been ages since I played mine) which means between DDing and buffing they don't get much free time to type, much like an alch dding, making potions, AoEing, etc.
__________________
'Ware fool, that you put too much stock in the power of the spoken word, ledt the unspoken one trample you from behind!